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Full text of "Text Book Of Mechanical Engineering"

Plate > eliding Rolls.                         297

powerful, consisting of wheels and pinions F G and H j, the last
being on 'the driving shaft, while M MN connect the rolls. The
pullies are driven by crossed and open straps, to obtain reversal,
K being the fast, and L L the loose pullies, so that either strap
may be put upon K alternately by a foot or hand lever attached
to the forks (not shewn). The plate to be bent is placed upon the
rolls A A? B lowered till a grip is obtained, and the machine set in
motion. When the plate has been drawn nearly through, the



machine is stopped, and the wheels EE given a slight, advance,
the rolls then reversed, and the plate brought back, and these
operations repeated until B is depressed enough to give the
necessary curvature. When the plate is' bent into an en tire "circle
It cannot be released at the front ; so the tof> of the standard is
made separate at P P, and the bolt Q turned down as shewn
dotted, when portion P F may be swung round horizontally upon
pin fc, leaving the bush g upon the roller B. The plate may then
be withdrawn. It should be noticed that the sides of the bushes
are curved in plan to radii from the pia R. '